diff --git a/kernel/debug.c b/kernel/debug.c
index e3497d54..006a65bb 100644
--- a/kernel/debug.c
+++ b/kernel/debug.c
@@ -88,6 +88,7 @@ int kprintf(const char *format, ...)
 	flags = ihk_mc_spinlock_lock(&kmsg_lock);
 
 	/* Copy into the local buf */
+	len = sprintf(buf, "[%3d]: ", ihk_mc_get_processor_id());
 	va_start(va, format);
 	len += vsnprintf(buf + len, KPRINTF_LOCAL_BUF_LEN - len - 2, format, va);
 	va_end(va);